Our major objective and aim for next year is contributing to RTOG performance by participating in various existing protocols and developing new studies. In addition to multimodality studies, we have tried to contribute protocols which answer specific questions of considerable importance to the radiation oncologist and his/her patients such as: (1) Is melanoma responsive to radiation therapy and are larger fractions more effective than conventional fractions? (2) Does surgical excision of solitary brain metastases add to palliation of radiation therapy? (3) Does a single pre-operative dose of 500 rad in the fixed portions of colorectal cancer enhance the effect of post-operative radiation? Does 500 rad have any effect in reducing systemic metastases from manipulation at the time of surgery? (4) Is it really necessary to give seminoma patients with positive lymph nodes below the diaphragm mediastinal and supraclavicular radiation therapy or might this interfere with future needed chemotherapy salvage in some patients? Our specific contribution would be in the hyperthermia field where we are exploring different methods of heating deep-seated tumors. We have demonstrated deep heating is possible with the circular electrode from the Magnetrode at 13.56 MHz. The heating patterns are not always uniform and optimal temperatures are oftentimes not achieved; unfortunately, the same is true with the BSD unit at University of Utah Medical Center. We have found some tumors are better heated with one unit, some with the other. Experience gained as a result of NCI contract to explore heating capacities of various units will be of considerable help to RTOG in future hyperthermia studies. We have attempted to use co-axial electrodes as an alternate to the circular electrode. To date we have found this neither better tolerated nor has it resulted in higher tolerable temperatures in the few patients in whom we utilized this alternative. Development of effective methods of thermometry with continuous and automatic recording of a multiprobe device which also allows mapping at 1-cm distance within the tumor is an important step forward. Equipment we are developing can be produced at a fraction of the cost of comparable commercially-available units and if perfected should save thousands of taxpayer dollars for every installation. We aim to double our own contribution over 1982 and, together with our old and new affiliates, to exceed 80 patients a year.